Don't access .spec on a !is_valid PUSH_PROMISE URL.

net/spdy/spdy_session.cc

Index: net/spdy/spdy_session.cc
diff --git a/net/spdy/spdy_session.cc b/net/spdy/spdy_session.cc
index edb1ae9b44877b08c4088e3f34ce45052d7e5cbf..bcde2ad1710088b8b1d70bec46e847483cb99105 100644
--- a/net/spdy/spdy_session.cc
+++ b/net/spdy/spdy_session.cc
@@ -2591,9 +2591,9 @@ void SpdySession::TryCreatePushStream(SpdyStreamId stream_id,
   // Verify that the response had a URL for us.
   GURL gurl = GetUrlFromHeaderBlock(headers);
   if (!gurl.is_valid()) {
-    EnqueueResetStreamFrame(stream_id, request_priority,
-                            ERROR_CODE_PROTOCOL_ERROR,
-                            "Pushed stream url was invalid: " + gurl.spec());
+    EnqueueResetStreamFrame(
+        stream_id, request_priority, ERROR_CODE_PROTOCOL_ERROR,
+        "Pushed stream url was invalid: " + gurl.possibly_invalid_spec());
     return;
   }